Guide rails are used on machine tools and, being wear parts, they have to be replaced from time to time. They are therefore frequently fixed on the machine frame with screws. To seal the radially widened end portions of the bores which receive the screw heads, it is known, for example from DE-OS 30 46 590 and DE-GM 93 16 349 to insert a plug or a cap into each end portion. The use of caps has the drawback of too low mechanical retention forces. In addition, this also requires a cost-intensive assembly because each cap has to be individually inserted.
It is also possible to provide a groove-like recess on the guide rail in alignment with the fixing bores and fit a cover strip into the recess. Such an arrangement is shown for example in DD-PS 237 805, in which the cover strip can be glued to the guide rail within the groove-shaped recess. However, there exists the danger of the glued joint getting disengaged.
In a linear motion guide known from DE-PS 43 11 641, a cover strip made of resilient strip material is slipped on to the guide rail whereby inwardly bent edge regions of the strip engage into undercuts of the guide rail. The undercuts are situated on the two parallel longitudinal surfaces of the guide rail, while the entire upper surface of the guide rail is covered by the cover strip. The drawback of this configuration is that the fixing of the cover strip on the guide rail is very unstable and the width of the strip must correspond to the entire width of the guide rail. Another drawback is that the cover strip can only be stocked in a spread-out state or in the form of a roll of very large diameter because, otherwise, an unfolding of the bent edges would impair the retaining function. Since the strip can only be rolled in a very large diameter, transportation is problematic. Furthermore, only thin strips can be used because they have to be guided over the side surfaces of the guide rail where only a small space is available. Thus only low retention forces are obtained. The strip can be pressed in over the through-apertures and can be easily disengaged even at the center of the rail. If the guide carriage is already installed on the guide rail, the mounting of the cover strip on the guide rail is only possible with great difficulty and with a reduction of the clamping forces.
A guide rail of the initially cited type is also known from EP-OS 0 311 895. In this case, the longitudinal groove on the upper surface of the rail needs to be only so wide that the inserted cover strip reliably seals the through-apertures of the guide rail which are spaced one behind the other in the longitudinal direction of the rail. The cover strip is glued on the guide rail to the bottom of the longitudinal groove between every two successive through-apertures. This results in a stable arrangement of the cover strip but it is not easy to disengage it again from the guide rail. When disengagement has been effected by applying a high force, both the cover strip and the guide rail have to be freed of the glue, for example by grinding.